Turbine blade

ABSTRACT

An airfoil profile is formed such that a passage width ratio, represented in a dimensionless manner, of an inter-blade passage width of vane root cross-section to an outlet throat width substantially monotonously decreases from a blade inlet toward a blade outlet. The blade has a blade airfoil profile shape in an envelope within a range of ±2.0 mm in a direction normal to any surface location of an airfoil profile portion. The airfoil profile portion has a reference airfoil contour represented in Cartesian coordinates, wherein Z is a distance representing a sectional height from a root of the airfoil profile portion. The contours represented by X and Y at each section Z are joined smoothly with one another in a blade height direction to form a complete shape of the airfoil profile portion.

CLAIM OF PRIORITY

The present application claims priority from Japanese Patent ApplicationNo. 2007-049931, filed Feb. 28, 2007 and is a continuation applicationof U.S. application Ser. No. 12/018,521, filed Jan. 23, 2008, thecontents of which are incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a turbine blade for a gas turbine andparticularly to an improvement in an airfoil profile of a first stageturbine blade.

2. Description of the Related Art

A gas turbine of this type that has generally been adopted is configuredsuch that working fluid compressed by a compressor is added with fueland burned to provide high-temperature and high-pressure working fluid,which drives a turbine. The rotational energy of the turbine thus drivenis usually converted into electric energy by a generator coupled to theturbine.

In recent years, more expectations have been placed on improvements inthe efficiency of a gas-turbine-and-steam-turbine-combined cycle. It hasbeen intended as one of the means to further increase the temperatureand pressure of the working fluid.

As regards a high-temperature turbine component, particularly, a firststage turbine blade, efforts have been made to provide an optimum shapewith respect to aerodynamic performance as well as to reinforce acooling structure in order to deal with increased high-temperature andhigh-pressure. For example, a shape of a first stage blade inairfoil-profile-height central cross-section is disclosed in anon-patent document, K. Kawaike, et. al.: Integrated CAE System forCooled Turbine Blade Design and Verification Tests of Analytical Codes:R. J. Goldstein, et. al., Proceedings of International Symposium HeatTransfer in Turbomachinery, Begall House, Inc. 1992.

Incidentally, JP-A-2004-108369 discloses one of the first stage airfoilprofiles of a gas turbine blade.

SUMMARY OF THE INVENTION

FIG. 6 illustrates an inter-blade passage width of a blade rootcross-section in a dimensionless manner with respect to a trailing edgethroat width (an outlet throat width) in the case where it is formed onthe basis of the airfoil profile of the first stage blade observed inthe above non-patent document. The inter-blade passage width formed insuch an airfoil is generally formed so as to monotonously increase froma blade inlet once, reach a peak and then monotonously decrease towardan outlet. The narrowest place in passage width is hydrodyanamicallycalled a throat. The inter-blade passage width mentioned above has twoplaces, a passage inlet and outlet, where their passage widths are eachnarrowed, which is hydrodyanamically called a double-throat. This willcause disturbed flows.

Incidentally, the divisional plane of the circumferential segment of ablade may be formed parallel to a rotor disk rotating shaft used tosecure the blade thereto. In such a case, also insertion grooves areformed parallel to the rotor disk rotating shaft; therefore, they caneasily be machined. This method is called an axial entry method, whichmakes blade assembly work easiest.

However, when a circumferential segment divisional plane 90 of a bladeas shown in FIG. 7 is formed parallel to a rotor disk rotating shaft(turbine rotating shaft) 50, a peak 71 of the airfoil back-side profileof a blade-root cross-section and a lowest point 72 of the airfoilventral-side profile adjacent thereto must be formed not to overlap eachother. This imposes a large limitation on airfoil design. Because ofthis limitation, the cross-section of the airfoil profile is generallysuch that the back-side peak is suppressed not to exceed the segmentdivisional plane 90, thus forming a round-shouldered, sublunate shape.Consequently, a double-throat is likely to be formed.

FIG. 8 illustrates the results of flow analysis on the inter-bladepassage configured on the basis of the airfoil profile of theconventional first blade. The passage width monotonously increases froma blade inlet to expand flow, thereby weakening restraint of the flow.Thus, extensive separation of flow 80 from the ventral surface 67 b ofthe airfoil profile 61 c occurs to increase an aerodynamic loss.Incidentally, reference numeral 65 b denotes a leading edge, 66 bdenotes a back surface and 68 b denotes a trailing edge.

It is an object of the present invention to provide a first stage bladeof a turbine blade having an aerodynamically optimum airfoil profilethat suppresses separation of flow from a blade ventral surface.

In the present invention, an airfoil profile is formed such that apassage width ratio, represented in a dimensionless manner, of aninter-blade passage width of vane root cross-section to a trailing edgethroat width (an outlet throat width) substantially monotonouslydecreases from a blade inlet toward a blade outlet. In this case,“substantially” means that a ratio of an inter-blade peak passage widthratio to a passage width ratio at the blade inlet is set to 1.05 orless. This is intended to avoid an influence caused by the inter-bladepassage width which monotonously increases once on the blade inlet side.

According to an aspect of the present invention, there is provided aturbine blade having a blade airfoil profile shape in an envelope withina range of ±2.0 mm in a direction normal to any surface location of anairfoil profile portion, wherein the airfoil profile portion has areference airfoil contour represented in Cartesian coordinates of X, Yand Z set forth in Tables 1 through 7 wherein the X, Y and Z aredistances in millimeters and the Z is a distance representing asectional height from a root of the airfoil profile portion, contoursrepresented by the X and Y at each section Z being joined smoothly withone another in a blade height direction to form a complete shape of theairfoil profile portion.

According to another aspect of the present invention, there is provide aturbine blade having a non-coated reference airfoil contour portionrepresented in Cartesian coordinates of X, Y and Z set forth in Tables 1through 7, wherein an airfoil profile portion of the turbine blade has areference contour represented in the Cartesian coordinates of X, Y and Zset forth in Tables 1 through 7 wherein the X, Y and Z are distances inmillimeters and the Z is a distance representing a sectional height froma root of the airfoil profile portion, contours represented by the X andY at each section Z being joined smoothly with one another in a bladeheight direction to form a complete shape of the airfoil profileportion. The X, Y and Z are scalable upwardly or downwardly as afunction of the same constant or number to provide an upwardly ordownwardly scaled airfoil profile portion.

Preferably, the root radius of the airfoil profile portion of the bladeis 493.9 mm, the height of the airfoil profile portion of the blade fromthe root radius is 77.1 mm, each of the root radius and the height ofthe airfoil profile portion has a tolerance of ±2.0 mm, and the turbinerotating body of the first stage blade is formed of eighty-two blades.

The present invention can provide an aerodynamically optimal airfoilprofile that can enhance the performance of the entire gas turbine.Specifically, in the first stage turbine blade, the inter-blade passagewidth is formed to substantially monotonously decrease from the bladeinlet toward the blade outlet. It is therefore possible to prevent flowseparation from the ventral surface of the airfoil profile whichotherwise occurs because the passage width monotonously increases toexpand the flow, thereby weakening restraint of the flow. Thus, anaerodynamic loss can be reduced. The present invention can provide anaerodynamically optimal airfoil profile that can eliminate flowseparation from the blade ventral surface, particularly, in the firststage turbine blade adopting the axial entry method.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates the entire system of a gas turbine on which a bladeaccording to an embodiment of the present invention is mounted.

FIG. 2 is a cross-sectional view of an essential portion of the turbineon which the blade of the embodiment is mounted.

FIG. 3 is a perspective view of the blade of the embodiment.

FIG. 4 illustrates an inter-blade passage width ratio of the blade ofthe embodiment.

FIG. 5 illustrates the results of inter-blade flow analysis with respectto the blade of the embodiment.

FIG. 6 illustrates an inter-blade passage width ratio of a conventionalblade.

FIG. 7 illustrates segment division of the blade.

FIG. 8 illustrates the results of inter-blade flow analysis with respectto a conventional blade.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

An embodiment of the present invention will hereinafter be described indetail with reference to the drawings. FIG. 1 illustrates the basicconfiguration of a gas turbine embodying the present invention. Aircompressed by a compressor 101 is supplied to a combustor 102. Thecombustor 102 burns fuel fed along with the compressed air to generatedrive fluid with high temperature and high pressure. A turbine 103 isdriven by this drive fluid, whereby electric power is taken out from agenerator 104 or a load. The drive fluid that performed its function inthe turbine 103 is discharged as exhaust gas to the outside. The statorblades and blades of the turbine 103 are forcibly cooled by air 105taken out of the compressor 101 to lower the metal temperature of bladematerial to an acceptable value or less.

FIG. 2 is a cross-sectional view of an essential portion (blade stageportion) of the turbine 103. A mainstream gas which is the drive fluidwith high temperature and high pressure is led to the inside of theturbine 103 from the exit of the combustor 102. The mainstream gassequentially flows down through a first stage consisting of a firststage stator blade 11 and a first stage blade 12 and through a secondstage consisting of a second stage stator blade 13 and a second stageblade 14 to drive the first blade 12 and the second blade 14.

The first stage blade 12 is secured to a first stage rotor disk 19, andthe second stage blade 14 is secured to a second stage rotor disk 20. Adisk spacer 21 is located between the first stage rotor disk 19 and thesecond stage rotor disk 20 so as to positionally correspond to thesecond stage stator blade 13. A distant piece 25 is secured integrallywith the first stage rotor disk 19, the disk spacer 21, the second stagerotor disk 20 and a stub shaft 30. These turbine components form arotating body as a rotor member.

The operating principle of the gas turbine is briefly described. Thedrive fluid caused by the compressor 101 and the combustor 102 to havehigh temperature and high pressure, that is, the mainstream gas,converts its high-pressure energy into flow velocity energy by the firststage stator blade 11 and second stage stator blade 13 constituting theturbine 103 to rotate the first stage blade 12 and the second stageblade 14, respectively. This rotational energy drives the generator 104to provide electric power. A portion of the rotational energy is alsoused to drive the compressor 101. In general the combustion temperatureof the turbine 103 varies depending on the heatproof temperature of theheat-resistant material of the gas turbine. However, the combustiontemperature of the turbine 103 is set so as to achieve high efficiencyin combination with a steam turbine. In the usual electricity-generatinggas turbine, a range of 1200° C. to 1500° C. is selected; on the otherhand, a pressure ratio of about 15 to 20 is selected. In this case, themainstream gas has a temperature equal to or higher than the allowabletemperatures of the blade materials of the first stage stator blade 11,the second stage stator blade 13, the first stage blade 12 and thesecond stage blade 14. It is therefore necessary to forcibly cool themby air 105 extracted from the compressor 101 and lower the metaltemperatures of the blade materials to allowable values or less.

FIG. 3 illustrates the first stage blade 12 of the present embodiment.The first stage blade 12 is composed of an airfoil profile portion 61located on the path of the mainstream gas, a shank portion 62, and adovetail portion 63 holding the blade on the first stage rotor disk 19.A cooling passage is formed inside the first stage blade 12 to cool theblade although not shown in the diagram. The airfoil profile portion 61is formed of a leading edge 65 located on the uppermost stream as viewedfrom a mainstream gas inflow direction 52, a back side 66 located on aleft-side protruding surface, a ventral side 67 located on a right-siderecessed surface, and a trailing edge 68 located on the lowermoststream. There are eighty-two first stage blades circumferentiallymounted to the first stage rotor disk 19 to constitute a first stageblade rotor. A blade segment divisional plane 92 of the first stageblade 12 is formed parallel to the rotor disk rotating shaft. Theinserting direction of the first stage blade 12 into the rotor disk isalso formed parallel to the rotor disk rotational axis. In this way, anaxial entry method is adopted.

As regards the airfoil profile portion 61, a turning angle 95 adapted tochange the direction of the drive fluid tends to increase in order toallow the mainstream gas with high temperature and high pressure toperform its function in an optimal manner. Also, the turning angleincreases from a blade tip to a blade root because of the radialdistribution of circumferential velocity. Thus, in general the turningangle is the largest at a blade root section. If the axial entry methodis adopted, the difficulty level of designing the airfoil avoiding adouble throat is high.

Next, FIG. 4 illustrates an inter-blade passage width of a blade rootcross-section represented in a dimensionless manner with respect to atrailing end throat width in the case where it is formed on the basis ofthe airfoil profile of the first stage blade 12 according to theembodiment. As is similar to the conventional example, the blade of thepresent embodiment is such that the inter-blade passage widthmonotonously increases once and subsequently decreases; however, a peakvalue itself is suppressed. In other words, the inter-blade passagewidth substantially monotonously decreases from the vane inlet to thevane outlet. Preferably, a ratio of a peak inter-blade passage widthratio 42 between blades to an intervene passage width ratio 41 of theblade inlet is 1.5 or less experimentally in order to suppress flowseparation from the blade profile ventral side. The blade of the presentembodiment suppresses the ratio to about 1.04, which satisfies thecondition.

FIG. 5 illustrates the results of flow analysis on the inter-bladepassage configured on the basis of the airfoil profile 61 b of the bladeaccording to the present embodiment. It can be observed that themodified passage width ratio suppresses flow separation from the ventralside 67 b of the airfoil profile. Thus, it is possible to reduce anaerodynamic loss that has otherwise occurred by utilizing the airfoilprofile of the blade according to the present embodiment, therebyimproving aerodynamic performance.

Next, a specific airfoil profile of the present invention defined on thebasis of the technical concept described above is provided in Tables 1through 7.

TABLE 1 Z = 0.0 X Y −25.13 −6.28 −25.91 −5.60 −26.51 −4.72 −26.88 −3.68−27.02 −2.55 −26.92 −1.37 −26.36 0.46 −25.24 2.83 −23.82 5.04 −22.137.05 −20.23 8.86 −18.14 10.45 −15.90 11.83 −13.54 12.97 −11.08 13.89−8.54 14.55 −5.94 14.94 −3.32 15.05 −0.71 14.88 1.86 14.41 4.37 13.646.77 12.59 9.05 11.29 11.17 9.75 13.14 8.02 14.96 6.14 16.64 4.12 18.202.01 19.64 −0.17 20.98 −2.43 22.24 −4.74 23.43 −7.08 24.56 −9.45 25.66−11.84 26.72 −14.24 27.76 −16.65 28.79 −19.07 29.33 −21.14 28.78 −21.8027.23 −21.46 26.20 −20.07 25.12 −18.72 23.98 −17.41 22.80 −16.16 21.5614.94 20.28 −13.78 18.96 −12.67 17.60 −11.60 16.20 −10.59 14.76 −9.6213.29 −8.71 11.79 −7.85 10.26 −7.05 8.70 −6.30 7.12 −5.61 5.51 −4.973.87 −4.40 2.22 −3.89 0.55 −3.45 −1.13 −3.08 −2.83 −2.78 −4.55 −2.56−6.27 −2.43 −8.00 −2.38 −9.73 −2.44 −11.45 −2.61 −13.15 −2.90 −14.82−3.34 −16.45 −3.93 −17.99 −4.72 −19.41 −5.69 −20.42 −6.35 −21.50 −6.78−22.61 −6.96 −23.69 −6.88 −24.68 −6.54

TABLE 2 Z = 6.0 X Y −24.76 −5.57 −25.53 −4.88 −26.10 −4.00 −26.46 −2.98−26.58 −1.86 −26.47 −0.69 −25.89 1.11 −24.76 3.45 −23.33 5.62 −21.657.59 −19.73 9.37 −17.64 10.93 −15.41 12.26 −13.05 13.36 −10.58 14.21−8.05 14.80 −5.47 15.10 −2.87 15.12 −0.29 14.84 2.24 14.26 4.68 13.377.01 12.22 9.21 10.83 11.26 9.22 13.16 7.44 14.91 5.52 16.53 3.49 18.021.37 19.42 −0.82 20.72 −3.08 21.94 −5.37 23.11 −7.70 24.23 −10.05 25.31−12.43 26.36 −14.81 27.40 −17.20 28.42 −19.60 28.96 −21.65 28.41 −22.3126.85 −21.96 25.85 −20.56 24.80 −19.19 23.70 −17.85 22.56 −16.56 21.37−15.31 20.14 −14.10 18.86 −12.93 17.55 −11.82 16.19 −10.75 14.80 −9.7313.37 −8.76 11.91 −7.85 10.41 −6.98 8.88 −6.18 7.33 −5.44 5.74 −4.754.13 −4.13 2.49 −3.58 0.83 −3.10 −0.84 −2.69 −2.53 −2.36 −4.24 −2.11−5.96 −1.95 −7.68 −1.89 −9.41 −1.93 −11.13 −2.07 −12.83 −2.35 −14.50−2.76 −16.13 −3.33 −17.68 −4.09 −19.11 −5.04 −20.11 −5.69 −21.19 −6.10−22.28 −6.27 −23.35 −6.17 −24.32 −5.83

TABLE 3 Z = 19.3 X Y −23.95 −3.98 −24.67 −3.30 −25.20 −2.44 −25.52 −1.44−25.61 −0.35 −25.47 0.77 −24.85 2.52 −23.70 4.79 −22.25 6.89 −20.55 8.79−18.63 10.47 −16.53 11.33 −14.29 13.15 −11.93 14.11 −9.47 14.81 −6.9615.21 −4.41 15.32 −1.87 15.12 0.61 14.60 3.02 13.79 5.32 12.68 7.4811.33 9.49 9.77 11.36 8.04 13.09 6.17 14.68 4.18 16.16 2.10 17.54 −0.0318.83 −2.23 20.05 −4.47 21.21 −6.74 22.33 −9.03 23.41 −11.35 24.46−13.68 25.49 −16.01 26.50 −18.35 27.50 −20.70 28.03 −22.74 27.47 −23.4025.91 −23.01 24.95 −21.59 23.97 −20.17 22.96 −18.78 21.91 −17.42 20.82−16.08 19.69 −14.78 18.53 −13.52 17.32 −12.29 16.07 −11.10 14.78 −9.9613.45 −8.87 12.08 −7.83 10.67 −6.85 9.22 −5.92 7.73 −5.06 6.21 −4.264.65 −3.53 3.06 −2.88 1.43 −2.30 −0.21 −1.81 −1.88 −1.41 −3.57 −1.10−5.28 −0.88 −6.99 −0.76 −8.71 −0.76 −10.43 −0.87 −12.14 −1.11 −13.81−1.48 −15.45 −2.02 −17.01 −2.73 −18.47 −3.64 −19.46 −4.23 −20.51 −4.60−21.57 −4.73 −22.59 −4.61 −23.53 −4.25

TABLE 4 Z = 38.5 X Y −22.81 −1.63 −23.48 −0.92 −23.96 −0.04 −24.21 0.95−24.23 2.03 −24.01 3.14 −23.29 4.79 −22.02 6.90 −20.50 8.82 −18.74 10.53−16.78 12.03 −14.67 13.29 −12.42 14.29 −10.08 15.01 −7.66 15.45 −5.2115.55 −2.77 15.33 −0.38 14.78 1.90 13.91 4.07 12.77 6.09 11.37 7.96 9.779.68 8.02 11.27 6.14 12.74 4.17 14.11 2.12 15.40 0.08 16.61 −2.08 17.77−4.25 18.88 −6.45 19.95 −8.67 20.99 −10.90 22.01 −13.14 23.01 −15.3824.00 −17.63 24.98 −19.89 25.95 −22.14 26.46 −24.15 25.89 −24.81 24.32−24.37 23.42 −22.91 22.52 −21.46 21.60 −20.01 20.67 −18.57 19.71 −17.1518.73 −15.74 17.72 −11.36 16.68 −13.00 15.60 −11.66 14.48 −10.37 13.32−9.10 12.11 −7.89 10.86 −6.72 9.56 −5.60 8.21 −4.55 6.81 −3.57 5.36−2.67 3.86 −1.82 2.31 −1.07 0.74 −0.41 −0.89 0.14 −2.55 0.57 −4.23 0.88−5.93 1.08 −7.64 1.16 −9.35 1.11 −11.06 0.93 −12.74 0.61 −14.38 0.12−15.96 −0.53 −17.43 −1.41 −18.41 −1.97 −19.46 −2.32 −20.51 −2.43 −21.51−2.29 −22.41 −1.90

TABLE 5 Z = 57.8 X Y −21.78 0.49 −22.38 1.22 −22.78 2.10 −22.95 3.10−22.88 4.15 −22.58 5.19 −21.75 6.73 −20.40 8.69 −18.83 10.48 −17.0512.06 −15.11 13.43 −13.01 14.54 −10.78 15.38 −8.47 15.90 −6.10 16.08−3.73 15.90 −1.43 15.35 0.77 14.48 2.83 13.33 4.74 11.91 6.49 10.30 8.108.56 9.59 6.71 10.96 4.78 12.25 2.78 13.46 0.74 14.61 −1.34 15.71 −3.4516.77 −5.57 17.79 −7.72 18.78 −9.88 19.76 −12.05 20.71 −14.23 21.65−16.41 22.59 −18.59 23.51 −20.78 24.43 −22.97 24.91 −24.94 24.32 −25.6022.75 −25.14 21.90 −23.68 21.05 −22.23 20.18 −20.79 19.31 −19.35 18.42−17.92 17.51 −16.50 16.59 −15.09 15.64 −13.70 14.67 −12.33 13.66 −10.9712.63 −9.64 11.56 −8.34 10.45 −7.06 9.30 −5.83 8.10 −4.65 6.85 −3.525.54 −2.45 4.18 −1.46 2.76 −0.56 1.27 0.24 −0.25 0.93 −1.84 1.51 −3.461.96 −5.12 2.27 −6.80 2.45 −8.48 2.49 −10.16 2.39 −11.83 2.14 −13.471.74 −15.05 1.16 −16.55 0.38 −17.53 −0.12 −18.56 −0.39 −19.59 −0.43−20.55 −0.23 −21.41 0.19

TABLE 6 Z = 71.0 X Y −21.01 1.78 −21.60 2.54 −21.97 3.45 −22.10 4.46−21.98 5.51 −21.62 6.55 −20.73 8.03 −19.33 9.88 −17.73 11.58 −15.9613.07 −14.01 14.35 −11.92 15.35 −9.71 16.06 −7.42 16.42 −5.10 16.40−2.82 15.98 −0.64 15.20 1.39 14.09 3.27 12.71 4.99 11.16 6.57 9.46 8.027.66 9.37 5.77 10.63 3.82 11.81 1.83 12.93 −0.19 14.01 −2.25 15.03 −4.3416.03 −6.44 16.99 −8.55 17.93 −10.67 18.86 −12.80 19.77 −14.94 20.67−17.08 21.56 −19.22 22.45 −21.36 23.34 −23.51 23.79 −25.46 23.20 −26.1121.63 −25.63 20.81 −24.19 19.99 −22.74 19.16 −21.30 18.32 −19.87 17.46−18.44 16.60 −17.01 15.73 −15.59 14.83 −14.19 13.92 −12.80 12.99 −11.4212.03 −10.06 11.04 −8.72 10.03 −7.41 8.97 −6.12 7.88 −4.87 6.74 −3.665.54 −2.50 4.30 −1.39 2.99 −0.36 1.62 0.58 0.19 1.43 −1.29 2.15 −2.842.74 −4.44 3.19 −6.08 3.48 −7.74 3.61 −9.40 3.57 −11.05 3.38 −12.68 3.02−14.25 2.47 −15.71 1.69 −16.71 1.16 −17.76 0.87 −18.81 0.82 −19.79 1.03−20.64 1.48

TABLE 7 Z = 77.1 X Y −20.64 2.35 −21.23 3.11 −21.60 4.03 −21.72 5.05−21.58 6.12 −21.20 7.16 −20.28 8.62 −18.86 10.43 −17.26 12.08 −15.4813.53 −13.53 14.76 −11.44 15.71 −9.24 16.35 −6.96 16.61 −4.67 16.48−2.44 15.94 −0.33 15.05 1.62 13.85 3.41 12.41 5.05 10.81 6.55 9.07 7.947.24 9.23 5.34 10.43 3.39 11.57 1.39 12.66 −0.62 13.69 −2.67 14.69 −4.7515.66 −6.83 16.60 −8.93 17.52 −11.03 18.43 −13.14 19.32 −15.26 20.20−17.38 21.08 −19.51 21.95 −21.63 22.82 −23.76 23.26 −25.70 22.66 −26.3521.10 −25.86 20.29 −24.42 19.48 −22.98 18.66 −21.54 17.84 −20.10 17.01−18.67 16.17 −17.24 15.31 −15.82 14.44 −14.41 13.56 −13.02 12.65 −11.6311.73 −10.26 10.78 −8.90 9.80 −7.56 8.79 −8.25 7.75 −4.97 6.66 −3.725.52 −2.51 4.34 −1.36 3.09 −0.26 1.78 0.74 0.40 1.66 −1.03 2.46 −2.553.13 −4.12 3.64 −5.74 3.99 −7.39 4.16 −9.04 4.16 −10.69 3.99 −12.31 3.63−13.87 3.09 −15.32 2.30 −16.32 1.75 −17.37 1.45 −18.42 1.39 −19.41 1.60−20.27 2.04

A Cartesian coordinate system of X and Y values given in Tables 1through 7 defines the airfoil profile 61 for each cross-section. Aheight from the root of the airfoil profile for each cross-section isrepresented with symbol Z. The values for the X and Y coordinates andsymbol Z are set forth in millimeters in Tables 1 through 7 althoughother units of dimensions may be used. In a blade of a preferableembodiment, a blade root radius is 493.9 mm, and a height from the bladeroot of the blade profile portion is 77.1 mm. A manufacturing toleranceis about ±2.0 mm for each of the blade root radius and the blade profileportion.

By defining X and Y coordinate values at selected locations in a Zdirection normal to the X, Y plane, the fundamental contour of theairfoil profile 61 can be ascertained. By connecting the X and Y valueswith smooth continuing arcs, each contour section at each sectionalheight Z is fixed. The contours of the airfoil profiles between eachcross-section are determined by smoothly connecting the adjacentcross-sections to one another to form the airfoil portion. These valuesrepresent the contours of the airfoil profile portion at ambient,non-operating or non-hot conditions and are for the uncoated airfoilportion.

The values in Tables 1 through 7 are generated and shown to the seconddecimal place for determining the contour of the airfoil profileportion. There are typical manufacturing tolerances as well as coatingswhich must be accounted for in the actual contour of the airfoil profileportion. Accordingly, the values for the contour given in Table 1 arefor a reference airfoil portion. Therefore, a distance of ±2 mm in adirection normal to any surface location along the contour of theairfoil profile portion defines the contour of the airfoil profileportion for this particular blade airfoil profile portion design andturbine.

It will be appreciated that the airfoil profile portion disclosed in theabove tables may be scaled up or down geometrically for use in othersimilar turbine designs. Consequently, the coordinate values set forthin Tables 1 through 7 may be scaled upwardly and downwardly such thatthe sectional shape of the airfoil profile portion remains unchanged.

The platform division angle of the blade in the present embodiment isformed parallel to the rotor disk rotating shaft but is not necessarilylimited to the complete parallelism. The platform division angle of theblade may also be formed approximately parallel to the rotor diskrotating shaft.

While the invention has been described in connection with what ispresently considered to be the most practical and preferred embodiment,it is to be understood that the invention is not to be limited to thedisclosed embodiment. The invention may be applied to blades conformingto the conditions, including the first stage turbine blade for a gasturbine.

1. A gas turbine comprising a turbine blade, the turbine blade having ablade airfoil profile portion, wherein the airfoil profile portion isformed such that a passage width ratio, represented in a dimensionlessmanner, of an inter-blade passage width of vane root cross-section to anoutlet throat width monotonously decreases toward a blade outlet aftermonotone increasing from a blade inlet; and is formed such that a ratioof a peak passage width ratio to a passage width ratio at the bladeinlet is set to 1.05 or less.
 2. The gas turbine according to claim 1,wherein the blade is secured to an insertion groove by an axial entrymethod, the insertion groove being formed on a rotor disk and parallelto the rotor disk rotating shaft; wherein a divisional plane of aplatform of the blade is formed approximately parallel to a direction ofturbine rotational axis; and wherein a peak of the airfoil back-sideprofile of a blade-root cross-section and a lowest point of the airfoilventral-side profile adjacent thereto are formed not to overlap eachother.
 3. The gas turbine according to claim 1, wherein the blade is afirst stage turbine blade.